When we publish papers, we hope they can get read, cited, or even built upon. It’s rare that a paper gets argued with in print and at length, which is probably a sign that the paper was worth writing! A couple of years ago, Henri Samuel, at the Institut de Physique du Globe de Paris, […]
A Molten Layer Above Mars’s Core Read More »
There are something like a hundred million unexploded landmines and pieces of ordnance in the ground worldwide, most of them small, shallow, and made of enough metal to have a magnetic signature. But reliably finding them with a magnetometer is far from easy. Heidi Myers, a former Ph.D. student co-advised by myself and Prof. Dan
The Gradiometer Has Finite Size Read More »
On Earth, a straightforward way of measuring the thickness of the crust beneath a seismometer is to look for converted waves — a P wave that turns into an S wave at the crust-mantle boundary. The method is simple, reliable, and used everywhere. On the Moon it has never really worked for P-to-S conversions. Apollo
A Method Built for Mars, Focused Back onto the Moon Read More »
Sitting at the very base of the mantle, directly beneath Hawai’i, is a patch of rock where seismic waves slow down dramatically. Structures like this — ultralow-velocity zones, or ULVZs — are found in many places along the core-mantle boundary, but the ones beneath major hot spots are exceptionally large, and their origin has been
An Iron-Rich Root Beneath Hawai’i Read More »
Bayesian sampling methods have entered the geophysical toolkit due to their versatility and power at quantifying uncertainty. Our lab has spent a decade contributing to them: transdimensional deconvolution of receiver functions, self-parameterizing inversions of surface waves, Bayesian tomography of North America and the inner core, etc. Regardless of the specific application, these methods return not
When the Average Isn’t a Solution Read More »
Three papers led by Jingchuan Wang (formerly a postdoc at Maryland, currently at Caltech) appeared in 2025 — one in JGR: Planets, one in Geophysical Research Letters, one in Earth and Space Science. They describe fieldwork at sites hundreds of miles apart and they read, at first glance, like three separate projects. But, all three
Rehearsing for the Moon Read More »
Eight years ago, the day after a magnitude 4.2 earthquake struck east of Dover, Delaware, graduate students from this lab were in the field installing seismometers alongside collaborators from the Carnegie Institution for Science, the Delaware Geological Survey, the U.S. Geological Survey, Lehigh University, and the Lamont-Doherty Earth Observatory. That deployment has now produced its
A Hidden Fault and Missing Aftershocks Beneath Delaware Bay Read More »
Mars has a liquid iron alloy core at its center. Using seismic data gathered by the InSight mission, we have made the first observations of seismic waves traveling through Mars’ core. We use the travel times of core-transiting seismic waves, relative to ones which remain in the mantle, to constrain properties of the core and
Constraints on Martian Core from First Observations of SKS Waves Read More »
Low-velocity layers within the crust can indicate the presence of melt and lithologic differences with implications for crustal composition and formation. Seismic wave conversions and reverberations across the base of the crust or intracrustal discontinuities, analysed using the receiver function method, can be used to constrain crustal layering. This is commonly accomplished by inverting receiver
Spurious Low Velocity Zones in Joint Inversions of Surface Waves and Receiver Functions Read More »
With collaborators Scott Burdick at Wayne State University and Lauren Waszek at New Mexico State University — both former Maryland postdocs — we just published the first tomographic model of Earth’s inner core in Earth and Planetary Science Letters. Seismic body wave and normal mode analyses have revealed that the inner core is solid, strongly
First Tomographic Model of the Inner Core! Read More »
